Experimental Study On The Deterioration Law Of Steel Slag Ballast

Under the trend of high-speed and high volume railway transportation,the phenomenon of ballast crushing and pulverization frequently occurs,causing the roadbed to gradually lose its elasticity and subsequently cause the roadbed to harden.The mechanical performance of the track bed has decreased,posing a threat to driving safety.Steel slag is a recycled material.Using steel slag as ballast for ballasted tracks can not only reduce environmental burden,but also create considerable economic benefits.However,at present,there is a lack of systematic research on the deterioration of steel slag during use and its impact on the decline of mechanical properties of the track bed.In this paper,the deterioration process of the first grade graded steel slag and the first grade ordinary crushed stone ballast is simulated through the progressive wear test and the indoor large-scale direct shear test,and the change laws of their abrasion resistance,crushing resistance and shear resistance are compared.Based on the variation pattern of particle breakage during the deterioration process of steel slag and the performance difference between steel slag and ordinary crushed stone ballast,an optimization method for improving the performance of steel slag is proposed.This method improves the situation of excessive particle breakage and insufficient shear strength in the development of steel slag deterioration.The specific research results are as follows:（1）During the degradation process of ballast,the wear resistance of steel slag is better than that of ordinary crushed stone ballast,but large-diameter steel slag is more prone to crushing and has a longer crushing duration than large-diameter ordinary crushed stone ballast.In the degradation of steel slag,particles with particle sizes of63-56mm and 35.5-25mm are more prone to fragmentation and have a greater degree of fragmentation;In the deterioration of ordinary crushed stone ballast,particles with a particle size of 25-16mm are more prone to breakage.When renovating or adding new ballast to railway line ballast,for steel slag lines,particles with a particle size of56-45mm should be mainly supplemented;In addition to supplementing large particle size particles,ordinary ballast lines should also appropriately supplement particles with particle sizes between 25-16mm.（2）Among the particles with a particle size less than 9.5mm produced by the deterioration of steel slag and ordinary crushed stone ballast,the main increase is that the particles with a particle size less than 1.7mm increase with the deterioration period.In addition,the mass of particles with a particle size less than 0.075mm generated by steel slag during the degradation process is about twice that of ordinary crushed stone ballast.In the assessment and cleaning of dirt on the track bed,special attention should be paid to the content of particles with particle sizes less than 9.5mm and less than 1.7mm;For steel slag lines,additional attention should be paid to the content of particles with a particle size less than 0.075mm.It is recommended to choose the dirt index PFI or the mass percentage of dirt particles P_9.5as the evaluation index and cleaning basis for steel slag.According to the dirt value and corresponding cleaning theory,the ballast cleaning should be carried out in a timely manner.（3）An optimization method has been proposed to improve the performance of steel slag.The optimized steel slag has better performance than first grade graded steel slag and first grade ordinary crushed stone ballast during the degradation process,and it is recommended to use it in engineering.For steel slag with different basic properties,refer to the basic properties and adjustment range of experimental steel slag for optimization and correction.